The present invention relates to an easily bendable tubing or hose for conducting or conveying two separate fluids, such as a liquid and a gas. Such xe2x80x9ctwo-channelxe2x80x9d flexible tubings are useful when two separate fluids are to be transported between different although interacting devices or pieces of equipment, which are so located or set up that the distance between them may fluctuate or vary m operation. Another reason for using such easily bendable tubing may be that at least one end thereof has to be connected and disconnected to an interacting device, or e.g. a living creature, from time to time and without difficulty or undue efforts.
In connection with e.g. automatic or semi-automatic milking it is well-known prior art to use a lightweight milking unit in the form of a cluster comprising a milk claw provided with four teatcups connected therewith. Each such teatcup is connected with the milk claw by means of the teatcup liner and a flexible vacuum tube or line for providing the pulsating vacuum within the teatcup.
In order to facilitate the handling of the cluster and the four teatcups thereofxe2x80x94especially during the connection and disconnection of the teatcups with/from the cow""s teatsxe2x80x94it is desirable that the liner""s hose-like milk discharge tube portion as well as the vacuum line are both easily bendable or flexible and constitute light-weight components. It is of course always highly desirable that the teatcups affect the teats with as low pulling and bending forces or loads as possible, so that a gentle treatment of the cow (and thereby optimal conditions for good udder health) can be obtained.
However, it is not possible to reduce the weight and stiffness of the liner""s hose-like milk discharge tube portion and the vacuum line merely by reducing the thickness of the wall of these two components, since a too small wall thickness will lead to an obvious risk that said tube portion and vacuum line will collapse during bending. This risk is of course particularly great for the vacuum line.
A primary object of the invention is to provide a new type of easily bendable tubing for conveying two separate fluids (or transferring pressure signals corresponding to the pressures of said fluids) without encountering the above mentioned risk of collapse of the walls of the tubes/lines.
The new type of xe2x80x9ctwo-channelxe2x80x9d tubing should preferably be suited for connecting the milk discharge end of a teatcup with a milk claw or any type of equipment (such as tubing or pipes) being part of a milking system, especially an automatic milking system.
However, a tubing of the present novel type may of course also be highly suitable for any use within the industry where an easily bendable tubing is required for hydraulic and/or pneumatic apparatus or machinery.
According to the present invention the above-mentioned objects are obtained with a tubing comprising two laterally spaced flexible tube means which are spaced apart and kept together alongside each other by connecting means between them, wherein on opposite sides of the tubing there are provided, in the tube wall of each tube means, transverse, spaced apart recesses arranged at the side of each other in a respective row along each tube means. The recesses in each tube means are constituted by straight grooves extending at right angles to the longitudinal axis of the tube means and being arranged at regular intervals along the tube means.
The xe2x80x9cstraight-groovexe2x80x9d layout of the recesses helps to optimize the xe2x80x9ceasy-to-bendxe2x80x9dxe2x80x94characteristics of the tubing.
The connecting means may comprise one or more connecting portions between the two tube means. Said connecting means may for example consist of only one continuous longitudinal web between the tube means, or of several consecutive, longitudinally spaced apart web portions arranged at equal or variable intervals in the region between the tube means. It is even possible to use connecting means in the form of some type of generally known connecting clip, e.g. clips of the type used within the area of hydraulics.
In a preferred embodiment of this type of tubing the tube means are spaced apart at a predetermined distance by a connecting means in the form of a flexible, bandshaped connecting web extending between and along the tube means and being located at least approximately in a plane containing the central longitudinal axes of the tube means, and the recesses comprise at least approximately mutually parallel grooves arranged at intervals of equal or variable size.
The intervals between the recesses in the rows along the tube means may be of different sizes in different parts or regions of the tubing.
A tubing having these features will constitute an easily bendable tubing which can be bent to a small radius without causing collapse of any of the two tube means thereof. Such tubing has proved to be very suitable e.g. as a fluid transfer hose between the milk discharge end of a teatcup and the milking system equipment connected thereto. When the teatcup is attached in use to a teat of an animal, it will hang down vertically from the teat, and the tubing leading from its discharge end will have to be smoothly bent upwards in the form of a U-shaped curve.
Another advantage with a xe2x80x9ctwo-channelxe2x80x9d tubing of this type is that it most effectively integratesxe2x80x94in one and the same constructive elementxe2x80x94the two tube means thereof. This will in effect make the use of such tubing most convenient, especially in connection with an automatic milking system wherein a milking robot is used for handling the teatcups.
Furthermore, to obtain as far as possible a non-distorted, non-warped bending configuration for the tubing, it is preferable that, on each side of the tubing, every recess in either tube means is directed in line with an adjacent recess in the other tube means.
From a xe2x80x9cstrength-of-materialxe2x80x9d point of view it may be convenient to use recesses having V-shaped cross-sections with a smoothly curved transitional bottom portion between the straight side flanks of the V-shape. The angle between the side flanks of the V-shape may preferably amount to about 60xc2x0.
If the thickness of the tube walls of the two tube means is e.g. 4,5 mm, it may be suitable to use recesses having a maximal depth of about 3,5 mm.
Preferably, a tubing according to the present invention may be produced by compression moulding of an elastomer.
When using a tubing according to the invention as a connecting tube element between a teatcup and another two-channel hose or other pipes of a milking system, one of the tube means will be adapted to conduct a liquid (i.e. milk), whereas the other tube means will be adapted to conduct a gas (i.e. air), the pressure of which fluctuates and is lower than the ambient atmospheric pressure.